Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 15 Dec 2023 16:23:11 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 2/2] sched/fair: take into account scheduling domain in select_idle_core() |
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On Thu, Dec 14, 2023 at 06:55:51PM +0100, Keisuke Nishimura wrote: > When picking out a CPU on a task wakeup, select_idle_smt() has to take > into account the scheduling domain where the function looks for the CPU. > This is because cpusets and isolcpus can remove CPUs from the domain > to isolate them from other SMT siblings.
Same question as before, when cpusets, the cpu should also be unset from p->cpus_ptr. So I'm thinking you're one of those isolcpus users I wish that would go away ;-)
> This change replaces the set of CPUs allowed to run the task from > p->cpus_ptr by the intersection of p->cpus_ptr and sched_domain_span(sd) > which is stored in the cpus argument provided by select_idle_cpu. > > Fixes: 9fe1f127b913 ("sched/fair: Merge select_idle_core/cpu()") > Signed-off-by: Keisuke Nishimura <keisuke.nishimura@inria.fr> > Signed-off-by: Julia Lawall <julia.lawall@inria.fr> > --- > kernel/sched/fair.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 71306b48cf68..3b7d32632674 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -7262,7 +7262,7 @@ static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpu > if (!available_idle_cpu(cpu)) { > idle = false; > if (*idle_cpu == -1) { > - if (sched_idle_cpu(cpu) && cpumask_test_cpu(cpu, p->cpus_ptr)) { > + if (sched_idle_cpu(cpu) && cpumask_test_cpu(cpu, cpus)) { > *idle_cpu = cpu; > break; > } > @@ -7270,7 +7270,7 @@ static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpu > } > break; > } > - if (*idle_cpu == -1 && cpumask_test_cpu(cpu, p->cpus_ptr)) > + if (*idle_cpu == -1 && cpumask_test_cpu(cpu, cpus)) > *idle_cpu = cpu; > }
Aside of that, the actual patch seems to be fine, just the rationale needs work.
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